Scoped

module Scoped where
open import Data.Nat using (;zero;suc;∣_-_∣)
open import Data.Fin using (Fin;zero;suc;toℕ)
open import Data.Integer.Show using () renaming (show to ishow)
open import Data.Vec using (Vec;[];_∷_)
open import Data.Bool using (Bool)
open import Data.Product using (_×_;_,_)
open import Relation.Binary.PropositionalEquality using (_≡_;refl)
open import Data.Sum using (_⊎_;inj₁)
open import Data.String using (String;_++_)

open import Builtin using (Builtin)
open Builtin.Builtin

open import Builtin.Signature using (_⊢♯;integer;bytestring)
open import Builtin.Constant.Type
open import Builtin.Constant.AtomicType using (aBool)

open import Raw using (RawTy;RawTm;RawTyCon)
open RawTy
open RawTm
open RawTyCon

open import Utils using (Kind;Maybe;nothing;just;maybe;Monad;Either;inj₁;inj₂;List;[];_∷_)
open Monad

open import RawU using (TyTag;TmCon;tmCon;tagCon2TmCon;tmCon2TagCon)
data ScopedTy (n : ) : Set where
  `    : Fin n  ScopedTy n
  _⇒_  : ScopedTy n  ScopedTy n  ScopedTy n
  Π    : Kind  ScopedTy (suc n)  ScopedTy n
  ƛ    : Kind  ScopedTy (suc n)  ScopedTy n
  _·_  : ScopedTy n  ScopedTy n  ScopedTy n
  con  : ∀{K}  TyCon K  ScopedTy n
  μ    : ScopedTy n  ScopedTy n  ScopedTy n
  SOP  : List (List (ScopedTy n))  ScopedTy n

Tel⋆ :     Set
Tel⋆ n m = Vec (ScopedTy n) m

-- contexts

data Weirdℕ :   Set where
  Z : Weirdℕ 0
  S : ∀{n}  Weirdℕ n   Weirdℕ n
  T : ∀{n}  Weirdℕ n  Weirdℕ (suc n)

-- variables

data WeirdFin : ∀{n}  Weirdℕ n  Set where
  Z : ∀{n}{w : Weirdℕ n}  WeirdFin (S w)
  S : ∀{n}{w : Weirdℕ n}  WeirdFin w  WeirdFin (S w)
  T : ∀{n}{w : Weirdℕ n}  WeirdFin w  WeirdFin (T w)


-- what is this for?
-- there are two meaningful things here:
-- 1. one to literally convert the number
-- 2. to extract a type context from a term one
-- this looks like (1)

wtoℕ : ∀{n}  Weirdℕ n  
wtoℕ Z = zero
wtoℕ (S x) = suc (wtoℕ x)
wtoℕ (T x) = suc (wtoℕ x)

WeirdFintoℕ : ∀{n}{w : Weirdℕ n}  WeirdFin w  
WeirdFintoℕ Z     = 0
WeirdFintoℕ (S i) = suc (WeirdFintoℕ i)
WeirdFintoℕ (T i) = WeirdFintoℕ i

-- extract number of term binders we are under
wtoℕTm : ∀{n}  Weirdℕ n  
wtoℕTm Z = zero
wtoℕTm (S x) = suc (wtoℕTm x)
wtoℕTm (T x) = wtoℕTm x

wtoℕTy : ∀{n}  Weirdℕ n  
wtoℕTy Z     = zero
wtoℕTy (S x) = wtoℕTm x
wtoℕTy (T x) = suc (wtoℕTm x)


-- extract the number of type binders

lookupWTm : ∀(x : ){n}(w : Weirdℕ n)  Maybe 
lookupWTm zero Z = nothing
lookupWTm zero (S w) = just 0
lookupWTm zero (T w) = nothing
lookupWTm (suc x) Z = nothing
lookupWTm (suc x) (S w) = fmap suc (lookupWTm x w)
lookupWTm (suc x) (T w) = lookupWTm x w

lookupWTy : ∀(x : ){n}(w : Weirdℕ n)  Maybe 
lookupWTy zero Z = nothing
lookupWTy zero (S w) = nothing
lookupWTy zero (T w) = just 0
lookupWTy (suc x) Z = nothing
lookupWTy (suc x) (S w) = lookupWTy x w
lookupWTy (suc x) (T w) = fmap suc (lookupWTy x w)


lookupWTm' : ∀(x : ){n}  Weirdℕ n  
lookupWTm' i Z = i
lookupWTm' zero (S w) = 1
lookupWTm' (suc i) (S w) = suc (lookupWTm' i w)
lookupWTm' i (T w) = suc (lookupWTm' i w)
{-
lookupWTm' x (S m) = lookupWTm' x m
lookupWTm' x (T m) = lookupWTm' (suc x) m
lookupWTm' x Z     = suc x
-}

lookupWTy' : ∀(x : ){n}  Weirdℕ n  
lookupWTy' i Z = i
lookupWTy' i (S w) = suc (lookupWTy' i w)
lookupWTy' (suc i) (T w) = suc (lookupWTy' i w)
lookupWTy' 0 (T w) = 1

{-
lookupWTy' x (S m) = lookupWTy' (suc x) m
lookupWTy' x (T m) = lookupWTy' x m
lookupWTy' x Z     = suc x
-}

-- these are renamings
shifterTy : ∀{n}(w : Weirdℕ n)  RawTy  RawTy
shifterTyList : ∀{n}(w : Weirdℕ n)  List RawTy  List RawTy
shifterTyListList : ∀{n}(w : Weirdℕ n)  List (List RawTy)  List (List RawTy)

shifterTy w (` x)     = ` (maybe (\x  x) 100 (lookupWTy  x - 1   w))
shifterTy w (A  B)   = shifterTy w A  shifterTy w B
shifterTy w (Π K A)   = Π K (shifterTy (T w) A)
shifterTy w (ƛ K A)   = ƛ K (shifterTy (T w) A)
shifterTy w (A · B)   = shifterTy w A · shifterTy w B
shifterTy w (con c)   = con c
shifterTy w (μ A B)   = μ (shifterTy w A) (shifterTy w B)
shifterTy w (SOP Tss) = SOP (shifterTyListList w Tss)

shifterTyList w [] = []
shifterTyList w (x  xs) = shifterTy w x  shifterTyList w xs

shifterTyListList w [] = []
shifterTyListList w (xs  xss) = shifterTyList w xs  shifterTyListList w xss

shifter : ∀{n}(w : Weirdℕ n)  RawTm  RawTm
shifterList : ∀{n}(w : Weirdℕ n)  List RawTm  List RawTm

shifter w (` x) = ` (maybe (\x  x) 100 (lookupWTm  x - 1  w))
shifter w (Λ K t) = Λ K (shifter (T w) t)
shifter w (t ·⋆ A) = shifter w t ·⋆ shifterTy w A
shifter w (ƛ A t) = ƛ (shifterTy (S w) A) (shifter (S w) t)
shifter w (t · u) = shifter w t · shifter w u
shifter w (con c) = con c
shifter w (error A) = error (shifterTy w A)
shifter w (builtin b) = builtin b
shifter w (wrap pat arg t) =
  wrap (shifterTy w pat) (shifterTy w arg) (shifter w t)
shifter w (unwrap t) = unwrap (shifter w t)
shifter w (constr A i cs) = constr (shifterTy w A) i (shifterList w cs)
shifter w (case A x cs) = case (shifterTy w A) (shifter w x) (shifterList w cs)

shifterList w [] = []
shifterList w (x  xs) = shifter w x  shifterList w xs

unshifterTy : ∀{n}  Weirdℕ n  RawTy  RawTy
unshifterTyList : ∀{n}(w : Weirdℕ n)  List RawTy  List RawTy
unshifterTyListList : ∀{n}(w : Weirdℕ n)  List (List RawTy)  List (List RawTy)

unshifterTy w (` x)     = ` (lookupWTy' x w)
unshifterTy w (A  B)   = unshifterTy w A  unshifterTy w B
unshifterTy w (Π K A)   = Π K (unshifterTy (T w) A)
unshifterTy w (ƛ K A)   = ƛ K (unshifterTy (T w) A)
unshifterTy w (A · B)   = unshifterTy w A · unshifterTy w B
unshifterTy w (con c)   = con c
unshifterTy w (μ A B)   = μ (unshifterTy w A) (unshifterTy w B)
unshifterTy w (SOP Tss) = SOP (unshifterTyListList w Tss)

unshifterTyList w [] = []
unshifterTyList w (x  xs) = unshifterTy w x  unshifterTyList w xs

unshifterTyListList w [] = []
unshifterTyListList w (xs  xss) = unshifterTyList w xs  unshifterTyListList w xss

unshifter : ∀{n}  Weirdℕ n  RawTm  RawTm
unshifterList : ∀{n}(w : Weirdℕ n)  List RawTm  List RawTm

unshifter w (` x) = ` (lookupWTm' x w)
unshifter w (Λ K t) = Λ K (unshifter (T w) t)
unshifter w (t ·⋆ A) = unshifter w t ·⋆ unshifterTy w A
unshifter w (ƛ A t) = ƛ (unshifterTy (S w) A) (unshifter (S w) t)
unshifter w (t · u) = unshifter w t · unshifter w u
unshifter w (con c) = con c
unshifter w (error A) = error (unshifterTy w A)
unshifter w (builtin b) = builtin b
unshifter w (wrap pat arg t) =
  wrap (unshifterTy w pat) (unshifterTy w arg) (unshifter w t)
unshifter w (unwrap t) = unwrap (unshifter w t)
unshifter w (constr A i cs) = constr (unshifterTy w A) i (unshifterList w cs)
unshifter w (case A t cs) = case (unshifterTy w A) (unshifter w t) (unshifterList w cs)

unshifterList w [] = []
unshifterList w (x  xs) = unshifter w x  unshifterList w xs

data ScopedTm {n}(w : Weirdℕ n) : Set where
  `    :    WeirdFin w  ScopedTm w
  Λ    :    Kind  ScopedTm (T w)  ScopedTm w
  _·⋆_ :    ScopedTm w  ScopedTy n  ScopedTm w
  ƛ    :    ScopedTy n  ScopedTm (S w)  ScopedTm w
  _·_  :    ScopedTm w  ScopedTm w  ScopedTm w
  con  :    TmCon  ScopedTm w
  error :   ScopedTy n  ScopedTm w
  builtin : (b : Builtin)  ScopedTm w
  wrap :    ScopedTy n  ScopedTy n  ScopedTm w  ScopedTm w
  unwrap :  ScopedTm w  ScopedTm w
  constr        : (A : ScopedTy n)  (i : )  (cs : List (ScopedTm w))  ScopedTm w
  case          : (A : ScopedTy n)  (arg : ScopedTm w)  (cs : List (ScopedTm w))  ScopedTm w

Tel : ∀{n}  Weirdℕ n    Set
Tel w n = Vec (ScopedTm w) n

-- SCOPE CHECKING / CONVERSION FROM RAW TO SCOPED

-- should just use ordinary kind for everything

postulate
  FreeVariableError : Set

{-# COMPILE GHC FreeVariableError = type FreeVariableError #-}


data ScopeError : Set where
  deBError : ScopeError
  freeVariableError : FreeVariableError  ScopeError

{-# FOREIGN GHC import PlutusCore.DeBruijn #-}
{-# FOREIGN GHC import Raw #-}
{-# COMPILE GHC ScopeError = data ScopeError (DeBError | FreeVariableError) #-}


ℕtoFin : ∀{n}    Either ScopeError (Fin n)
ℕtoFin {zero}  _       = inj₁ deBError
ℕtoFin {suc m} zero    = return zero
ℕtoFin {suc m} (suc n) = fmap suc (ℕtoFin n)

ℕtoWeirdFin : ∀{n}{w : Weirdℕ n}    Either ScopeError (WeirdFin w)
ℕtoWeirdFin {w = Z}   n    = inj₁ deBError
ℕtoWeirdFin {w = S w} zero = return Z
ℕtoWeirdFin {w = S w} (suc n) = do
  i  ℕtoWeirdFin {w = w} n
  return (S i)
ℕtoWeirdFin {w = T w} n  = do
  i  ℕtoWeirdFin {w = w} n
  return (T i)

scopeCheckTy : ∀{n}  RawTy  Either ScopeError (ScopedTy n)
scopeCheckTyList : ∀{n}  List RawTy  Either ScopeError (List (ScopedTy n))
scopeCheckTyListList : ∀{n}  List (List RawTy)  Either ScopeError (List (List (ScopedTy n)))

scopeCheckTy (` x) = fmap ` (ℕtoFin x)
scopeCheckTy (A  B) = do
  A  scopeCheckTy A
  B  scopeCheckTy B
  return (A  B)
scopeCheckTy (Π K A) = fmap (Π K) (scopeCheckTy A)
scopeCheckTy (ƛ K A) = fmap (ƛ K) (scopeCheckTy A)
scopeCheckTy (A · B) = do
  A  scopeCheckTy A
  B  scopeCheckTy B
  return (A · B)
scopeCheckTy (con (atomic x)) = return (con (atomic x))
scopeCheckTy (con list) = return (con list)
scopeCheckTy (con pair) = return (con pair)
scopeCheckTy (μ A B) = do
  A  scopeCheckTy A
  B  scopeCheckTy B
  return (μ A B)
scopeCheckTy (SOP xss) = do
      A  scopeCheckTyListList xss
      return (SOP A)

scopeCheckTyList [] = return []
scopeCheckTyList (x  xs) = do
      A   scopeCheckTy x
      As  scopeCheckTyList xs
      return (A  As)

scopeCheckTyListList [] = return []
scopeCheckTyListList (xs  xss) = do
      Ts   scopeCheckTyList xs
      Tss  scopeCheckTyListList xss
      return (Ts  Tss)

scopeCheckTm : ∀{n}{w : Weirdℕ n}  RawTm  Either ScopeError (ScopedTm w)
scopeCheckTmList : ∀{n}{w : Weirdℕ n}  List RawTm  Either ScopeError (List (ScopedTm w))

scopeCheckTm (` x) = fmap ` (ℕtoWeirdFin x)
scopeCheckTm {n}{w}(Λ K t) = fmap (Λ K) (scopeCheckTm {suc n}{T w} t)
scopeCheckTm (t ·⋆ A) = do
  A  scopeCheckTy A
  t  scopeCheckTm t
  return (t ·⋆ A)
scopeCheckTm (ƛ A t) = do
  A  scopeCheckTy A
  t  scopeCheckTm t
  return (ƛ A t)
scopeCheckTm (t · u) = do
  t  scopeCheckTm t
  u  scopeCheckTm u
  return (t · u)
scopeCheckTm (con c) = return (con (tagCon2TmCon c))
scopeCheckTm (builtin b) = return (builtin b)
scopeCheckTm (error A) = fmap error (scopeCheckTy A)
scopeCheckTm (wrap A B t) = do
  A  scopeCheckTy A
  B  scopeCheckTy B
  t  scopeCheckTm t
  return (wrap A B t)
scopeCheckTm (unwrap t) = fmap unwrap (scopeCheckTm t)
scopeCheckTm (constr A i cs) = do
  A   scopeCheckTy A
  cs  scopeCheckTmList cs
  return (constr A i cs)
scopeCheckTm (case A t cs) = do
  A   scopeCheckTy A
  t   scopeCheckTm t
  cs  scopeCheckTmList cs
  return (case A t cs)

scopeCheckTmList [] = return []
scopeCheckTmList (x  xs) = do
  x   scopeCheckTm x
  xs  scopeCheckTmList xs
  return (x  xs)
extricateScopeTy : ∀{n}  ScopedTy n  RawTy
extricateScopeTyList : ∀{n}  List (ScopedTy n)  List RawTy
extricateScopeTyListList : ∀{n}  List (List (ScopedTy n))  List (List RawTy)

extricateScopeTy (` x)      = ` (toℕ x)
extricateScopeTy (A  B)    = extricateScopeTy A  extricateScopeTy B
extricateScopeTy (Π K A)    = Π K (extricateScopeTy A)
extricateScopeTy (ƛ K A)    = ƛ K (extricateScopeTy A)
extricateScopeTy (A · B)    = extricateScopeTy A · extricateScopeTy B
extricateScopeTy (con (atomic x)) = con (atomic x)
extricateScopeTy (con list) = con list
extricateScopeTy (con pair) = con pair
extricateScopeTy (μ A B)    = μ (extricateScopeTy A) (extricateScopeTy B)
extricateScopeTy (SOP Tss)  = SOP (extricateScopeTyListList Tss)

extricateScopeTyList [] = []
extricateScopeTyList (x  xs) = extricateScopeTy x  extricateScopeTyList xs

extricateScopeTyListList [] = []
extricateScopeTyListList (xs  xss) = extricateScopeTyList xs  extricateScopeTyListList xss

extricateScope : ∀{n}{w : Weirdℕ n}  ScopedTm w  RawTm
extricateScopeList  : ∀{n}{w : Weirdℕ n}  List (ScopedTm w)  List RawTm

extricateScope (` x) = ` (WeirdFintoℕ x)
extricateScope (Λ K t) = Λ K (extricateScope t)
extricateScope (t ·⋆ A) = extricateScope t ·⋆ extricateScopeTy A
extricateScope (ƛ A t) = ƛ (extricateScopeTy A) (extricateScope t)
extricateScope (t · u) = extricateScope t · extricateScope u
extricateScope (con c) = con (tmCon2TagCon c)
extricateScope (error A) = error (extricateScopeTy A)
extricateScope (builtin bn) = builtin bn
extricateScope (wrap pat arg t) =
  wrap (extricateScopeTy pat) (extricateScopeTy arg) (extricateScope t)
extricateScope (unwrap t) = unwrap (extricateScope t)
extricateScope (constr A i cs) = constr (extricateScopeTy A) i (extricateScopeList cs)
extricateScope (case A x cs) = case (extricateScopeTy A) (extricateScope x) (extricateScopeList cs)

extricateScopeList [] = []
extricateScopeList (x  xs) = extricateScope x  extricateScopeList xs

– UGLY PRINTING

uglyWeirdFin : ∀{n}{w : Weirdℕ n}  WeirdFin w  String
uglyWeirdFin Z = "0"
uglyWeirdFin (T x) = "(T " ++ uglyWeirdFin x ++ ")"
uglyWeirdFin (S x) = "(S " ++ uglyWeirdFin x ++ ")"

uglyTmCon : TmCon  String
uglyTmCon (tmCon integer x) = "(integer " ++ ishow x ++ ")"
uglyTmCon (tmCon bytestring x) = "bytestring"
uglyTmCon size = "size"


postulate showNat :   String

{-# FOREIGN GHC import qualified Data.Text as T #-}
{-# COMPILE GHC showNat = T.pack . show #-}

uglyBuiltin : Builtin  String
uglyBuiltin addInteger = "addInteger"
uglyBuiltin _ = "other"
ugly : ∀{n}{w : Weirdℕ n}  ScopedTm w  String
ugly (` x) = "(` " ++ uglyWeirdFin x ++ ")"
ugly (ƛ _ t) = "(ƛ " ++ ugly t ++ ")"
ugly (t · u) = "( " ++ ugly t ++ " · " ++ ugly u ++ ")"
ugly (Λ _ t) = "(Λ " ++ ugly t ++ ")"
ugly (t ·⋆ A) = "( " ++ ugly t ++ " ·⋆ " ++ "TYPE" ++ ")"

ugly (con c) = "(con " -- ++ uglyTermCon c ++ ")"
ugly (builtin b) = "builtin " ++ uglyBuiltin b
{-  "(builtin " ++
  uglyBuiltin b ++
  " " ++
  ishow (Data.Integer.ℤ.pos (Data.List.length As)) ++
  " " ++
  ishow (Data.Integer.ℤ.pos (Data.List.length ts))
  ++ ")" -}
ugly (error _) = "error _"
ugly (wrap _ _ t) = "(wrap " ++ ugly t ++ ")"
ugly (unwrap t) = "(unwrap " ++ ugly t ++ ")"
ugly (constr A i cs) = "constr" -- TODO: Do it better
ugly (case A x cs)   = "case"   -- TODO: Do it better